Artificial aid for improving hearing



ARTI

1,611,130 v. o.f KNUDsEN E-r AL FICIAL AID FOR K- IMPROVING HEARING 'III' III i223. 8. l6il ibn/aya.

jnes? l `Patented 14, l1926.

i UNITED! STATES PATENT orifice.

vnms o. xmmsmi AND ISAAC mamans, 'or Los ANGELES, cALIroImIA.

AnrrrIcIAI. ron. mrnovme HEARING.

Application mea october 22, 1924. serial No. 745,240.

Our invention relates to a new artificial aid'for improving the hearing of those who are partially deaf. This instrument which we have chosen to term a 'magnaphone, em- 5 -ploys a vacuumtube ampliiier similar-to those`used in telephone and radio practice. v It diers from all-.other artificial aids to hearing Yin a noveland an important'manner.; namely each amplifier is designed to Y 14 0 amplify selectively tonesl of diierent pitch according to' a prescription which is deter-` mined by precise audiometric tests on -the person for whom the instrument is designed. This selective amplification is effected by Y 15 introducing an electrical correction circuit between the two stages of the amplifier, and is of such designV as will vgive the type of .amplification needed to correct'the hearing defects in each Vindividual case of deafness. The primary object of this invention is to provide a more effective means for aiding those who are partially deaf and particu- 'larl -in providing the exact ampliication nee ed in each individual case.v y

vIn the accompanying drawing forming part of this specification, Fig. 1 is a dlagrammatic view of our invention vshowing the form of circuit employed, it being understood that other forms of circuits may be used without departing rom the spirit'o our invention; Figs-2 to 5 inclusive are diagrams. of several correction circuitswhich may be used for variously amplifylngthe fre uency components of speech according to t e nature and degree ot'- hearing defect ineach individual case of deafness,vand Figs. f 6to l0 inclusive are hearing charts showing v t es of deafness.

ie general arrangement of Va typical'eircuit embodying' our invention is shown in Fig. 1. It-eonsists of a 'two stage vacuum tube amplifier embodying the audion tubes A and B which-J are connected in the usual mannerl wit-h telephone transmitter `C and telephone receiver,` D 4in lits input and output, respective] TheA receiver and transmitt'eI-are pre erably of high quality and highly damped design. 'Between' the two stages of the ampliier there 1s placed a filter E which as shown is in the :formof a cortance 11 and a. resistance '12. These are conf nectdin Fig. 1 in series across'the input of 55..thevacuum tube amplier B.

rection circuit which lconsists of various A combinations of aninductance 10, a capaci-- The necessity for selective amplification may be shown by referring to Figs. 6 lto 10,

which 4show the acuity of the hearing function for i ive types' of deafness. The horizontal axis G in each 'of the hearing charts represents the response of a Vnormal ear to i tones of dlerent pitch. The frequencles ot' these tonesV are represented by the numbers along this axis. The numbers along the vertical axis Hl In eachchart rcpresent'the degrecs of deafness on a numerical scale. For

example, inchart Figo, at a frequency ot' -500 double vibrations per second, there is a depression of 100 units which means -that the amplitude of a barely. audible tone for the ear represented' by chart' Fig. 6 must be 100 times' the amplitude for. a barely audible tone of the same pitch for a normal car. Hence 'in chart Fig. 6 there is'represented a type of deafness in which all .tones are equally depressed. lnchart Fig. Zvthere is represented a typical case of nerve deafness,

in which casel tones of. low pitch are heard l.

almost normally well, but the auditory acuity for the tones of'high pitch is verypoor.

In chart Fig.- 8 there vis represented a -typi- -cal ease of lixation deafness, ^where the tones of low pitch are depressed-the more and the tones 'of high pitch are heard almost no1-- mally welh- Chart Fig' represents a moreunusual type of deafness in which tones ol low pitch and also'tones of high. pitch are depressed more than the tonesof medium pitch. Chart Fig.. 10 'representsa type et' deafness in which there is a tonal' island;

that is, a case in which the auditory acuity is relatively insensitive over a narrow hand of frequencies. v

` The'chart's in Figs; 6 to '10 illustrate strikingly the futility of attempting to usev the same artificial aid for4 correcting different.

dividual i case of deafness requires a pre` scribed ltype of simplificationsA A n artiical aid which might be helpful', to a person types of deafness.' As these charts show, -eachgtypeof deafnessand probably cachinwhosehearing'" function is similaito that y represented by chart Flg. 7 might be worse than 'nothing tofa person who had a typ;` of deafnessrepresented chart Fig. bf.. For cases of deafness like those 'represented in-ch'art Fig. 7, the high frequency components mustbe given greater amplification than the low frequency components. For

cases of deafness' similarito thosev represented bychartaFig. 8, it is4 the low frequencies whichareluire relatively more .amplification than the igh frequencies.

In Fig. 1 the correction circuitv shown between the Vtwo stages of the instrument is designedV to amplify selectively high fre'- quencies more than lowv frequencies. In Figs. 2 to 5 inclusive, correction circuits are shown with various' combinations and arrangements of the inductance 10, capacitance 11' and resistancey 12. In Fig.` 2 capacitance 11 is 'placed between the resistance 12, and inductance '10. AThis arrangement is I vadapted for selectively amplifying low frequencies andis adapted for usewhen confnected in the circuit, in place of the filter shown in Fig. 1 in cases of fixational deafness such as illustrated by the chart Fig. 8. In Fig. 3 another arran' ementof the inductance, i resistance an shown connected across` the input of the audion bulb B which will amplify the low and high frequency components of speech such as will benefit the hearing of those affiicted with fixation and nerve deafness as illustrated in chart Fig. l9. f Other 'arrangements vand modifications of the correction circuits are also shown in Figs. 4 and 5, it being understood that applicants do not wish to limitifthemselves to these typical filters which are intended to be adaptable to the magnaphone circuit according to the articular purpose lfor which they are inten ed.

The mannerin which these artificial laids to hearing may bebprescribed'and designed is as follows: otologists or" others qualifiedm to make audiometric testsv would obtaina precise charting ofthe hearing function for the person who4 ,desires Aan artificial aid.

.This'ch'art could be sent to a central office or factory l,where an expert would design the type of amplifier 4necessary to correct the defects shown-by eachchart. There is thus capacitance is p afforded ya service for prescribing and designing "aids to hearing foreach individual case of deafness. If binaural hearing is to be restored, each ear will require a separate amplifier. If the person is 4content with monaural hearing, a single amplifier is all that is needed.

stages of the amplifier to selectivel amplify certain frequencies for use wit certain characteristics of deafness. f

2. In combination with a two stage vacuum tubeamplifier circuit` containing au! dion tubes and a transmitter 'and a receiver connected with the input and output respectively, and a corrective circuit containing an inductance and a resistance placed in series between the two stages of the amplifier to selectively. amplify certain "frequenciesfor applications of use with certain characteristics of deafness.

3. In combination with a two stage vacuum tube amplifier circuit containing audlon tubes and a transmitter and a receiver connected with the .i input and. output respectively, 'and a corrective circuit containingan inducta'nce and a capacitance placed -in series between the two stages of the amplifier to selectively amplify .certainn frequencies for applications of use with certain"characteristics of deafness.

vERN `o. KNUDSEN. ISAAC H. JONES. 

